1. Technological Field
The present disclosure relates generally to the field of content and/or data delivery over a network. More particularly, the present disclosure is related, in one exemplary aspect, to methods and apparatus for asymmetric distribution of mixed content via a network, such as a passive optical network (PON). In one exemplary embodiment, a PON is configured to deliver different services (e.g., Ethernet over PON (EPON) and Radio Frequency over Glass (RFoG)) to differently sized service groups, via a common fiber optic plant.
2. Description of Related Technology
The provision of content to a plurality of subscribers in a content distribution network is well known in the prior art. In a typical configuration, the content is distributed to the subscribers devices over any number of different topologies including for example: (i) Hybrid Fiber Coaxial (HFC) network, which may include e.g., dense wave division multiplexed (DWDM) optical portions, coaxial cable portions, and other types of bearer media; (ii) satellite network (e.g., from an orbital entity to a user's STB via a satellite dish); (iii) optical fiber distribution networks such as e.g., “Fiber to the X” or FTTx (which may include for example FTTH, FTTC, FTTN, and FTTB variants thereof); (iv) Hybrid Fiber/copper or “HFCu” networks (e.g., a fiber-optic distribution network, with node or last-mile delivery being over installed POTS/PSTN phone wiring or CAT-5 cabling); (v) microwave/millimeter wave systems; etc.
Service providers, and more specifically, multiple system operators (MSOs), continually strive to increase the data capacity of their networks to increase revenue. Many MSOs have migrated to optical technologies by replacing the coax portion of existing Hybrid Fiber Coax (HFC) networks with a single-fiber Passive Optical Network (PON). Exemplary networks utilize different optical wavelengths in the downstream (e.g., to the consumer premises) and upstream directions (e.g., from the consumer premises). Typically, optical networks use 1550 nm, 1490 nm, and 1577 nm in the downstream direction, and 1310 nm, 1270 nm, and 1610 nm in the upstream direction. The upstream return path allows the fiber infrastructure to support both RFoG (Radio Frequency over Glass) and PONs simultaneously.
In conventional Optical Distribution Networks (ODNs), so-called Optical Network Units (ONUs) (also referred to RFoG ONUs (R-ONUs), Optical Network Terminals (ONTs) and/or “micronodes” in RFoG networks) are typically deployed at each of multiple customer premises locations. In a conventional optical network, a single strand of optical fiber is typically shared among multiple downstream ONUs (typically 32, but other numbers are possible). In the downstream direction, a light splitting resource divides downstream light power to the ONUs such that a portion of the downstream light power is transmitted to each ONU. Each of the ONUs receives light containing identical information in the downstream direction (from the service provider to a corresponding subscriber customer). Typically, a signal analyzer analyzes the received signal to determine which data is directed to the corresponding subscriber. In certain instances, a portion of content encoded on a respective downstream optical signal can include data available for consumption by multiple subscribers.
For upstream transmissions (customer to service provider), each of the ONUs can include a respective laser transmitter that is manufactured to identical specifications. As such, the transmitters transmit on the same or nearly identical wavelength of light in the upstream direction to the service provider. Even though two transmitters on the same wavelength cannot transmit at the same time; two transmitters on different wavelengths can transmit at the same time. Each wavelength is separately received by a corresponding receiver. An optical detection device in the upstream optical receiver converts the optical signal into a respective electrical output that is proportional to the instantaneous sum of the combined optical powers contributed by the two lasers.
Installation of fiber optics is very expensive, thus ODN infrastructures multiplex multiple optical services over the same underlying optical “plant” (i.e., physical infrastructure). Specifically, existing schemes for multiplexing and combining optical signals assume the same service group size for all the signals being transmitted on the ODN/PON. Unfortunately, while each user-technology is treated uniformly in terms of physical distribution, each user-technology has specific requirements and cost structures. Consequently, some services are over-subscribed, while other services are under-subscribed. For example, consumers that receive RFoG services also receive Ethernet over PON (EPON) services, even though RFoG is more profitable and can support more users than EPON.
Coupling different user-technologies together also significantly complicates repair, maintenance, and upgrades to capital equipment. In particular, changes in the configuration of one user-technology will result in a disruption of service to the other coupled user-technologies. For example, a change in the EPON service group size might force a disruption to the customers using Coarse Wavelength Division Multiplexing (CWDM) Ethernet, the latter of which are usually higher-value customers).
Ideally, service providers seek to optimize different user-technology services (e.g., EPON, RFoG, etc.) so as to maximize customer expectations, within the operating constraints of the ODN. In particular, rather than splitting all user-technology services out to all users indiscriminately, each user or service group (e.g., a neighborhood, etc.) should receive only the services to which they have subscribed and/or can be delivered in a cost efficient manner. More generally, solutions are needed for asymmetric distribution of mixed content via a network, such as a passive optical network.